Monday, October 31, 2005

Expandable clay minerals can act like a primordial womb to protect and promote synthesis of organic molecules. On the early Earth, volcanic gases were emitted onto the seafloor from vents where carbon dioxide and hydrogen interact with metallic minerals to form methanol, a one carbon organic molecule. The temperature of this environment (>300°C [475°F]) would have been too high for most organic molecules to survive. However, clay minerals are commonly found in these volcanic vents, and expandable clay minerals (smectite), with silicate sheets stacked like a deck of cards, will adsorb and protect organics between the sheets. The clay mineral surfaces often promote organic reactions.

Williams et al. tested the potential for clays to not only protect methanol in hot water, but to synthesize new compounds needed as building blocks for more complex biomolecules. Volcanic vent simulations showed that certain expandable clays react quickly at 300°C to a non-expandable form, and the mineralogical changes coincide with production of a large number of complex organic molecules, primarily ring-structures (e.g., hexamethyl-benzene), some with up to 20 carbon atoms. The importance of this work is that it shows a potential mineralogical control on organic molecule evolution that could have been an important step in the origin of life.

On this day is 1992, the Vatican admitted erring for over 359 years in formally condemning Galileo Galilei for entertaining scientific truths such as the Earth revolves around the sun it, which the Roman Catholic Church long denounced as anti-scriptural heresy.

After 13 years of inquiry, the Pope's commission of historic, scientific and theological scholars brought the pope a "not guilty" finding for Galileo. Pope John Paul II himself met with the Pontifical Academy of Sciences to help set the record straight. In 1633, at age 69, Galileo was forced by the Roman Inquisition to repent and spent the last eight years of his life under house arrest. Galileo was a 17th century Italian mathematician, astronomer and physicist remembered as one of history's greatest scientists.

Sunday, October 30, 2005

October 30, 1820 - November 20, 1899Dawson was a Canadian geologist who made numerous contributions to paleobotany and extended the knowledge of Canadian geology. Dawson was born and raised in Pictou, Nova Scotia, where the many sandstone and coal formations provided fertile ground for his first scientific explorations, which culminated in the publication of Acadian Geology. He made many important discoveries of fossil life, great and small. These included fossil plants, trackways of lowly invertebrates, footprints, skeletons of reptiles and amphibians, millipedes and the earliest land snails. When the famous geologist Charles Lyell visited coal deposits in Pictou, Dawson acted as his guide.

In 1851, Dawson and Lyell teamed up again to examine the interiors of fossil tree trunks at Joggins, Nova Scotia. They discovered the remains of some of the earliest known reptiles, Hylonomus lyelli, along with other rare fossils, propelling this part of the world into the international spotlight. Dawson became principal of McGill College in Montreal in 1854, which he made into a reputable institution. He remained there, teaching geology and palaeontology and acting as librarian, until his retirement. One of his lifelong dreams was realized in 1882 when Peter Redpath gave money to McGill for the construction and establishment of a museum, naming Dawson as director. Today the Peter Redpath Museum of Natural History houses many specimens from Dawson's personal collection.

"That's lightning-fast," said co-author Craig Moritz, professor of integrative biology at UC Berkeley and director of the Museum of Vertebrate Zoology. "To find a recently evolved species like this is exceptional, at least in my experience."

The yet-to-be- named species arose after two isolated populations of the green-eyed tree frog reestablished contact less than 8,000 years ago and found that their hybrid offspring were less viable. To avoid hybridizing with the wrong frogs and ensure healthy offspring, one group of females preferentially chose mates from their own lineage. Over several thousand years, this behavior created a reproductively isolated population - essentially a new species - that is unable to mate with either of the original frog populations.

This example suggests that rapid speciation is often driven by recontact between long-isolated populations, Moritz said. Random drift between isolated populations can produce small variations over millions of years, whereas recontact can amplify the difference over several thousands of years to generate a distinct species.

"The overarching question is: Why are there so many species in the tropics?" Moritz said. "This work has led me to think that the reason is complex topography with lots of valleys and steep slopes, where you have species meeting in lots of little pockets, so that you get all these independent evolutionary experiments going on. Perhaps that helps explain why places like the Andes are so extraordinarily diverse."

Because of geographic isolation that began between 1 and 2 million years ago with the retreat of rainforest to higher elevations, two separate frog lineages developed in the northern and southern parts of the species' coastal range - only to be reconnected less than 8,000 years ago as the climate got wetter and warmer and the rainforest expanded.

Saturday, October 29, 2005

This beautiful photo of the the Late Cretaceous of the Kaiparowits Plateau in Grand Staircase-Escalante National Monument, Utah, was taken (and stitched together from four images) by William Monteleone. You're looking at over 6000 ft. of exposure!.

Bill Monteleone is a wonderful artist/sculptor whose work will be of interest to any reader of this blog. I'll be featuring more about Bill in the near future, but for now you can check out his work at his LOST ART studio site.

In a new book, The Plausibility of Life: Resolving Darwin's Dilemma, Harvard Medical School's Marc W. Kirschner and John C. Gerhart, of the University of California–Berkeley address a key problem in evolutionary theory that has puzzled scientists from Darwin on and which is now under intense scrutiny by proponents of intelligent design: where do the big jumps come from in evolution? Kirschner, HMS professor and chair of the Dept. of Systems Biology, and Gerhart show that newly discovered molecular properties of organisms facilitate evolution.

The origin of novelty, the development of new arrangements of interlocking parts that some call "irreducibly complex," can only be understood in the light of the last 20 years of research in cell biology and development.

We now know that the 'parts' that make up a living organism are very unlike the rigid parts designed for machines. Instead, they can flexibly connect and re-connect, using the same pieces over and over to make new functions.

For example, one might think that a mutation that makes the neck of a giraffe longer would have to be accompanied by several other mutations, one that expands the length of the muscles of the neck, another that makes the blood vessels longer, and so on. But instead, the muscles grow to fit the length of the bone and the blood vessels grow until all the muscles have a sufficient supply of oxygen. Apparently very complex adaptations can therefore be achieved with few, simple mutations.Today, it is understood for the first time that all animals use the same set of core processes to develop into adult forms. Applying this knowledge to evolution, the authors show that novel traits emerge from the ways the organism is constructed: its complex mechanisms for adapting to the environment, its modular construction, and its internal circuitry that can be re-specified and reconnected.

Thursday, October 27, 2005

After last week’s SVP conference I took part in the field trip to look at the Late Cretaceous of the Kaiparowits Plateau, Grand Staircase-Escalante National Monument in Utah. Trip leaders Alan Titus from the GS-ENM, Dr. Scott Sampson from the Utah Museum of Natural History, and Dr. David Gillette from the Museum of Northern Arizona organized a great trip and deserve a hearty pat on the back.

The Grand Staircase-Escalante National Monument has some of the most jaw-droppingly beautiful badlands I've ever seen, and I've seen a lot. Because much of it is still unexplored almost every new dinosaur find is a new species -- incredible!

Below are some photos from the trip. Enjoy!

The interpretive center at Bigwater. The building is shaped like an ammonite but this is only visible from the air.

Scott Sampson explains it all.

Mike Getty from the Utah Museum of Natural History & Alan Titus give a tour of a hadrosaur specimen in the Wahweap Formation.

Hadrosaur skin impression from the Kaiparowits Fm.

A fossilized tree in the Wahweap Fm. The root ball is at the left and the tree is pointing down the palaeostream.

Alan Titus uncovers skin impressions from the Kaiparowits Fm.

Some of the skin impression that Alan uncovered. Note that Larry Witmer's business card can double as a scale bar when flipped over -- a nifty idea!

Dave Gillette talks about his beloved plesiosaurs.

Dr. Don Henderson from the University of Calgary.

Scott Sampson and Mike Getty at a microsite. One of the best parts of the trip was the opportunity to get caught up with Scott & Mike after much too long a time.

Great white and other carnivorous sharks may have reputations for being cold-blooded killers but it turns out they have more in common with humans and other warm-blooded animals than previously believed, according to a new study involving a University of Calgary biologist released today.

In a paper (below) published in the Oct. 27th edition of the prestigious scientific journal Nature, U of Calgary muscle physiologist Dr. Douglas Syme and colleagues from around North America present evidence that a species of lamnid shark – the shark family comprised of predatory sharks like great whites and makos – has muscle tissue that functions much the same way as mammalian muscles, which allows for swifter and more powerful swimming motion relative to other fishes.

That finding led Syme and his team to conclude that the salmon shark (Lamna ditropis) appears unique in the fish world because it must maintain a much higher body temperature than the environment in which it lives– a trait normally associated with warm-blooded, or endothermic, creatures like mammals and birds.

Unlike mammals, which have developed complex insulation and thermoregulation systems to maintain constantly warm bodies, however, the salmon shark must rely on continuous movement to generate enough heat to survive.

Dr. Doug Syme and student hard at work.

“It’s very remarkable. It’s like having a mammal’s muscle in a shark,” Syme said. “They are warm, which gives them a significant advantage over their prey because warm muscle produces a lot of power, but it also puts them on a razor’s edge because if they cool down too much, their muscles stop working and they may well die,” he said. “They’ve crossed over the line to relying on endothermy, where they have to stay warm all the time. For a fish, and particularly one that lives in very cold water, this is extraordinary”

Syme said the common belief that sharks are primitive animals that have existed without major evoluntionary changes for millions of years, is untrue, and the study shows one of example of this.

“Sharks are an ancient group of animals but this shows they are not stuck in the past and are very successful in many environments,” Syme said. “These animals are keeping pace with their prey, salmon, which is a modern and very agile fish.

Abstract:Effects of temperature on muscle contraction and powering movement are profound, outwardly obvious, and of great consequence to survival. To cope with the effects of environmental temperature fluctuations, endothermic birds and mammals maintain a relatively warm and constant body temperature, whereas most fishes and other vertebrates are ectothermic and conform to their thermal niche, compromising performance at colder temperatures. However, within the fishes the tunas and lamnid sharks deviate from the ectothermic strategy, maintaining elevated core body temperatures that presumably confer physiological advantages for their roles as fast and continuously swimming pelagic predators.

Here we show that the salmon shark, a lamnid inhabiting cold, north Pacific waters, has become so specialized for endothermy that its red, aerobic, locomotor muscles, which power continuous swimming, seem mammal-like, functioning only within a markedly elevated temperature range (20–30 °C). These muscles are ineffectual if exposed to the cool water temperatures, and when warmed even 10 °C above ambient they still produce only 25–50% of the power produced at 26 °C. In contrast, the white muscles, powering burst swimming, do not show such a marked thermal dependence and work well across a wide range of temperatures.

Congrats to Doug Syme, one of my former Ph.D. advisors for this fine piece of research!

Abstract:Kelvin calculated the age of the Earth to be about 24 million years by assuming conductive cooling from being fully molten to its current state. Although simplistic, his result is interesting in the context of the dramatic cooling that took place after the putative Moon-forming giant impact, which contributed the final 10 per cent of the Earth's mass.

The rate of accretion and core segregation on Earth as deduced from the U–Pb system is much slower than that obtained from Hf–W systematics, and implies substantial accretion after the Moon-forming impact, which occurred 45 5 Myr after the beginning of the Solar System.

Here we propose an explanation for the two timescales. We suggest that the Hf–W timescale reflects the principal phase of core-formation before the giant impact. Crystallization of silicate perovskite in the lower mantle during this phase produced Fe3+, which was released during the giant impact10, and this oxidation resulted in late segregation of sulphur-rich metal into which Pb dissolved readily, setting the younger U–Pb age of the Earth. Separation of the latter metal then occurred 30 10 Myr after the Moon-forming impact.

Over this time span, in surprising agreement with Kelvin's result, the Earth cooled by about 4,000 K in returning from a fully molten to a partially crystalline state.

According to paleontologist Sankar Chatterjee and retired aeronautical engineer R.J. Templin, a small early Chinese dinosaur called Microraptor gui used a two-level, biplane wing configuration to fly from tree to tree in the early Cretaceous. Among the evidence for the early biplane is that Microraptor had unmistakable flight feathers on its hind limbs as well as on its wings, says Chatterjee, a distinguished professor at Texas Tech University in Lubbock. The Chinese paleontologists who first reconstructed Microraptor had guessed that its four wings were used in tandem, similar to those of dragonfly.

“The most unusual thing is that they have flight feathers not only on the hand section, but also on foot,” said Chatterjee. Flight feathers differ noticeably from other feathers in that they are asymmetrical with interlocking barbules to keep their shape. The leading edge of each long feather was narrower than the trailing edge, which helped streamline the body in flight. The hooked, interlocking barbs gave strength and flexibility to the feather and prevented air from passing through it in flight.

Another key element to discovering Microraptor’s flight secrets was setting some realistic limitations on how the dinosaur could move its hindlimbs – something that was initially overlooked by Chinese researchers who found the fossil. Chatterjee and Templin studied its anatomy and found that like any dinosaur, Microraptor held their hindlimbs in erect, vertical plane, permitting forward and backward motion.

Figure 2. Skeleton of Microraptor gui, a feathered dinosaur from the early Cretaceous (about 125 million years old) of China has preserved traces of feathers in the wings and legs, suggesting a biplane configuration. The animal was about 30 inches long with a bony tail and weighed about 2 pounds (courtesy: Dr. Xing Xu)

“The problem we faced is that the legs of Microraptor, like on any dinosaur, could not be splayed sideways,” as the Chinese paleontologists assumed. That means Microraptor could not have extended its rear limbs to form a wing directly behind the front wing. More likely, and more aerodynamically stable, would have been a rear wing that was held lower than the front wing – what from the side would look like a staggered biplane configuration, Chatterjee explains.

Chatterjee and Templin fed Microraptor’s flight data into a computer simulation that they have previously used to successfully analyze the flying abilities of pterosaurs and Archaeopteryx. Based on the aeronautical analysis, it appears that Microraptor flights looked rather like those seen today among some “monoplane” forest birds -- something called undulating phugoid gliding, Chatterjee said. In other words, Microraptor launched from a high branch and dove off, falling head-first until it reached a speed that created lift on its wings. With that lift the feathered dino then swooped upwards and landed in the branches of another tree without having to flap its wings and expend muscular energy.

“The biplane wing configuration was probably a very first experiment in nature,” says Chatterjee of the early flying technique, which was also used by another feathered dinosaur from China, Pedopenna, he said. Archaeopteryx achieved fully powered flight with monoplane configuration, as its wing became even larger than those of Microraptor, but foot feathers were lost.

The tracks of a previously unknown, two-legged swimming dinosaur have been identified along the shoreline of an ancient inland sea that covered Wyoming 165 million years ago, according to a University of Colorado at Boulder graduate student.

The illustration shows a swimming dinosaur leaving deep, complete footprints in shallow water and incomplete footprints as it gradually loses contact with the sea floor. Illustration courtesy Debra Mickelson.

Debra Mickelson of CU-Boulder's geological sciences department said the research team identified the tracks of the six-foot-tall, bipedal dinosaur at a number of sites in northern Wyoming, including the Bighorn Canyon National Recreation Area. "It was about the size of an ostrich, and it was a meat-eater," she said. "The tracks suggest it waded along the shoreline and swam offshore, perhaps to feed on fish or carrion."

"The swimming dinosaur had four limbs and it walked on its hind legs, which each had three toes," Mickelson said. "The tracks show how it became more buoyant as it waded into deeper water -- the full footprints gradually become half-footprints and then only claw marks."

Our Mongolia crew gave us lessions in their beautiful written language by writing in the dust on our vehicles.

Don, Julie and Darren.

Don prospects the cliffs.

Maryann and Didier work the Gallimimus quarry.

Didier forgot his hat this day. Not a good thing under the 40+ degree centigrade sun!

Henry and Mary work on a concertion containing parts of several Tarbosaurus lower legs and feet.

This block (seen in the lower right of the previous picture) is a concretion contaning yet another Tarbosaurus! -- you're looking at a partial vertebral column in cross-section. The poachers appear to have set this block up as a landmark for other specimens in the area.

Abstract: The evolutionary history of Maniraptora, the clade of carnivorous dinosaurs that includes birds and the sickle-clawed Dromaeosauridae, has hitherto been largely restricted to Late Jurassic and Cretaceous deposits on northern continents. The stunning Early Cretaceous diversity of maniraptorans from Liaoning, China, coupled with a longevity implied by derived Late Jurassic forms such as Archaeopteryx, pushes the origins of maniraptoran lineages back to Pangaean times and engenders the possibility that such lineages existed in Gondwana. A few intriguing, but incomplete, maniraptoran specimens have been reported from South America, Africa and Madagascar. Their affinities remain contested, however, and they have been interpreted as biogeographic anomalies relative to other faunal components of these land-masses. Here we describe a near-complete, small dromaeosaurid that is both the most complete and the earliest member of the Maniraptora from South America, and which provides new evidence for a unique Gondwanan lineage of Dromaeosauridae with an origin predating the separation between northern and southern landmasses.

The discovery of a bird-like dinosaur in South America has paleontologists rethinking when, where and how one group of raptors evolved. The rooster-sized dinosaur is called Buitreraptor (bwee-tree-rap-tor) gonzalezorum. It has a long head and long tail and wing-like forelimbs. Its serrated teeth, like steak knives, suggest it was a carnivore.Buitreraptor is related to Velociraptor, the presumed cunning killer made famous by Hollywood. Both belong to a class of birdlike dinosaurs that ran swiftly on two legs and are called dromaeosaurs. The new find suggests such raptors go back much further in time that previously thought.

Until recently, dromaeosaurs had been found only in Asia and North America and only in the Cretaceous period, which ran from 145 million to 65 million years ago. Evidence that they existed in the Southern Hemisphere has been mounting.

"Buitreraptor is one of those special fossils that tells a bigger story about the Earth's history and the timing of evolutionary events," said Peter Makovicky, Curator of Dinosaurs at The Field Museum. "It not only provides definitive evidence for a more global distribution and a longer history for dromaeosaurs than was previously known, but also suggests that dromaeosaurs on northern and southern continents took different evolutionary routes after the landmasses they occupied drifted apart."

The skeleton of Buitreraptor gonzalezorum in the field. A string of vertebrae and the right shoulder (lower left) and femur are showing. The matchstick shows scale. Photo by Peter Makovicky, Courtesy of the Field Museum.

Abstract:Dromaeosaurid theropod dinosaurs possess a strongly recurved, hypertrophied and hyperextensible ungual claw on pedal digit II. This feature is usually suggested to have functioned as a device for disembowelling herbivorous dinosaurs during predation. However, modelling of dromaeosaurid hindlimb function using a robotic model and comparison of pedal ungual morphology with extant analogue taxa both indicate that this distinctive claw did not function as a slashing weapon, but may have acted as an aid to prey capture.

Velociraptor, made famous by the Hollywood movie Jurassic Park, may not have been quite the super-efficient killer we all thought. Like other dinos in its family, it had a distinctive sickle-shaped claw on the second toe which many have assumed was employed to disembowel victims. But tests on a mechanical arm suggest this fearsome-looking appendage was probably used just to hang on to prey.

"This dispels the myth in place for some 40 years that this was a disembowelling claw - this is not the case," says Dr Phil Manning, from the Manchester Museum, University of Manchester.

"I'm saying that the primary function of this claw was to hold on to the prey, effectively like a climber's crampon," the curator of palaeontology told the BBC News website.

By kicking and slashing, it has been widely thought these creatures could quickly open up their unfortunate victims, either killing them outright or making them bleed so profusely death followed very quickly. Dr Manning and his team tested the reputation on a robotic arm fitted with a life-like dromaeosaur claw. The set-up was based on detailed fossil measurements.

The fossil teeth and jawbones of two new species of tiny monkey-like creatures that lived 37 million years ago have been sifted from ancient sediments in the Egyptian desert, researchers have reported.

They said their findings firmly establish that the common ancestor of living anthropoids -- including monkeys, apes and humans -- arose in Africa and that the group had already begun branching into many species by that time. Also, they said, one of the creatures appears to have been nocturnal, the first example of a nocturnal early anthropoid.

Erik Seiffert and his co-authors published their discovery of the two new species -- named Biretia fayumensis and Biretia megalopsis -- in an article in the October 14, 2005, issue of the journal Science.

The researchers discovered the fossils over the course of the last few years at a site called Birket Qarun Locality 2 (BQ-2) about 60 miles southwest of Cairo in the Fayum desert. BQ-2 has only been systematically excavated for about four years, said Seiffert, in contrast to a much younger Fayum site, called L-41, which has been explored for the last 22 years by Simons and his colleagues.

The latest fossils of the new species consist of tiny teeth and jaws, whose shapes yield critical clues about the species whose mouths they once occupied. For example, a tooth root from the species Biretia megalopsis is truncated, indicating that it had to make room for the larger eyesocket of a nocturnal animal.

"These finds seem to indicate that Biretia megalopsis must have had very large eyes, and so was likely nocturnal," said Seiffert. "This has never been documented in an early anthropoid. The simplest explanation is that Biretia's nocturnality represents an evolutionary reversal from a diurnal ancestor, but that conclusion is based solely on the probable pattern of relationships. If down the road we find out that our phylogeny was wrong, Biretia could end up being very significant for our understanding of the origin of anthropoid activity patterns."